What is the emergency function of the brake system primarily designed for?

The emergency function of the brake system is specifically designed to bring the train to an immediate stop. This function is crucial in situations where there is an urgent need to halt the train quickly to prevent accidents or respond to emergencies, such as encountering an obstacle on the tracks or a signal indicating danger.

Unlike the primary braking system, which might be used for routine speed control or gradual deceleration, the emergency brake is engineered to activate swiftly and effectively, utilizing maximum braking force. This capability ensures that the train can stop in the shortest distance possible, thereby enhancing the safety of passengers, crew, and rail operations.

The other options relate to different braking functions. Slowing down gradually is a standard operation for regular stops, maintaining speed does not pertain to braking functions, and steering assistance is not a role of the braking system, as trains are generally guided by tracks.